Lineup, this stage reflects K.I.S.S. principle that may be properly applied to audio design as well. When people run for symmetrical distortions they run against Mother - Nature that generates symmetrical distortions only when mechanical oscillating systems are abused. Also, designs that show higher THD on lower powers are again go against Mother Nature: the louder is the sound in reality, the reacher it is with harmonics.

People who run for symmetrical distorting amplifiers that distort symmetrically and the more distort the less is loudness, hawe to feed the sound to some Matrix robot, instead of to real human ears and bodies.

Too bad the transistors are not marked in your schematic, but fortunately we can make educated guesses . BTW shouldn't V4, V6 be BD135 (not BC135)?

Oops... Sure, BD135 - the same as in lineup's version!

Probably, a current mirror instead of R9 containing a diode and resistor in series will improve current source's linearity, but anyway it has much higher dynamic resistance than resistors in Lineup's design, so let's leave it as is and try this way.

No success, I yesterday tried to simulate your circuit, and I wasnīt able to get it working, I couldnīt achieve the output stage to have some reasonable current through it, the mosfet doesnīt open enough.

I am not sure if I didnīt make any mistakes when redraving the picture, the output stage is quite complicated.

BTW you forgot to nuber the transistors, so I canīt tell vhere the stated voltages should be. Also the mosfet is a little bit ambigious, but as it is IRF610, it should be N-type with source pointing down, right?

Originally posted by kubeek No success, I yesterday tried to simulate your circuit, and I wasnīt able to get it working, I couldnīt achieve the output stage to have some reasonable current through it, the mosfet doesnīt open enough.

I am not sure if I didnīt make any mistakes when redraving the picture, the output stage is quite complicated.

The output stage is actually very simple, though uncommon:

At top: FET and BJT followers in parallel. When "MOSFET does not open enough" BJT emitter follower does the job.

At bottom: current source, current depends on input voltage, R7 and beta of right bottom BJT transistor.

What load did you try it on?

Idle current depends on R7. 3.9K on 4v gives approximately 1 mA.
If beta of current amplifier (bottom right transistor) is 100, idle current will be 100 mA. Maximum peak current will be (8V/3.9K)*100 = 200 mA. It means, 6/0.2=12 Ohm minimal load impedance. Good enough for 32 Ohm headphones.

However, if you are going to drive speaker, or lower impedance headphones, or beta of transistor is much smaller than 100, you will need to adjust R7 value.